/*
  需求：防止按钮在短时间内被多次点击，使用节流函数限制规定时间内只能点击一次。
  思路：
    1、第一次点击，立即调用方法并禁用按钮，等延迟结束再次激活按钮
    2、将需要触发的方法绑定在指令上
  
  使用：给 Dom 加上 v-throttle 及回调函数即可
  <button v-throttle="debounceClick">节流提交</button>
*/
import type { Directive, DirectiveBinding } from 'vue'
interface ElType extends HTMLElement {
  __handleClick__: () => any
  disabled: boolean
}
const throttle: Directive = {
  bind(el: ElType, binding: DirectiveBinding<Function>) {
    if (typeof binding.value !== "function") {
      throw "callback must be a function"
    }
    let timer: NodeJS.Timeout | null = null
    el.__handleClick__ = function () {
      if (timer) {
        clearTimeout(timer)
      }
      if (!el.disabled) {
        el.disabled = true
        binding.value()
        timer = setTimeout(() => {
          el.disabled = false
          }, 1000)
        }
    }
    el.addEventListener('click', el.__handleClick__)
  },
  unbind(el: ElType) {
    el.removeEventListener('click', el.__handleClick__)
  }
}

export default throttle